The invention concerns a device for the exchange of a developer mixture found in a developer station which is used for the development of charge images applied on an intermediate carrier in the case of printing or copying devices.
Printing and copying devices which operate according to the electrostatic principle are known (see, for example, U.S. Pat. No. 3,331,592, incorporated herein by reference). In the case of these devices, charge images of the characters to be printed are generated on an intermediate carrier, for example, a drum with an electrophotographic layer. The charge carriers following this proceed to a developer station in which the charge images are developed and thus are made visible. For the development, a developer mixture is used which contains toner particles which are attracted by the charge images to the intermediate carrier. Following this, the developed charge images are transferred to a recording medium, for example a paper web, and are fixed there.
For the development of the charge images, mainly a two-component developer is employed. A serious disadvantage of this technology is the dropoff of the print quality arising by means of the aging of the developer mixture during the service life of the developer. In order to avoid too strong a dropoff of the print quality, previously the entire developer was exchanged at specific maintenance intervals. However, it could not be prevented that during operation, the printing quality continuously dropped off from a certain initial value.